I've never heard of them called "pseudo idioms", but here are a few more paired-up words: Namby-pamby, hither-thither, goods and chattels, hither and yon, suited and booted, peace and quiet, tooth and nail, vim and vigour... There are many, many more

http://books.google.com/books?id=GYwLAQAAIAAJ&pg=RA5-PA42 Although it is about advertising, page 42 of this book has some examples of alliteration which may interest you.